首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   4708篇
  免费   322篇
  国内免费   96篇
化学   2636篇
晶体学   21篇
力学   322篇
数学   289篇
物理学   1858篇
  2023年   201篇
  2022年   121篇
  2021年   193篇
  2020年   298篇
  2019年   118篇
  2018年   134篇
  2017年   345篇
  2016年   271篇
  2015年   234篇
  2014年   316篇
  2013年   307篇
  2012年   306篇
  2011年   257篇
  2010年   273篇
  2009年   231篇
  2008年   157篇
  2007年   157篇
  2006年   160篇
  2005年   169篇
  2004年   99篇
  2003年   94篇
  2002年   88篇
  2001年   166篇
  2000年   72篇
  1999年   128篇
  1998年   92篇
  1997年   59篇
  1996年   42篇
  1995年   3篇
  1994年   1篇
  1993年   2篇
  1992年   2篇
  1991年   3篇
  1990年   4篇
  1989年   5篇
  1988年   2篇
  1987年   2篇
  1986年   2篇
  1985年   5篇
  1984年   2篇
  1981年   2篇
  1977年   1篇
  1974年   2篇
排序方式: 共有5126条查询结果,搜索用时 946 毫秒
91.
Zeolitic imidazolate framework (ZIF) hybrid fluorescent nanoparticles and ZIF antibody conjugates have been synthesized, characterized, and employed in lateral-flow immunoassay (LFIA). The bright fluorescence of the conjugates and the possibility to tailor their mobility gives a huge potential for diagnostic assays. An enzyme-linked immunosorbent assay (ELISA) with horseradish peroxidase (HRP) as label, proved the integrity, stability, and dispersibility of the antibody conjugates, LC-MS/MS provided evidence that a covalent link was established between these metal-organic frameworks and lysine residues in IgG antibodies.  相似文献   
92.
The behavior of hyperelastic energies depending on an internal parameter, which is a function of the deformation gradient, is discussed. As an example, the analysis of two models where the parameter describes the activation of a tetanized skeletal muscle tissue is presented. In those models, the activation parameter depends on the strain and it is shown the importance of considering the derivative of the parameter with respect to the strain in order to capture the proper stress–strain relations.  相似文献   
93.
94.
95.
96.
97.
Herein, the pivotal role of secondary nucleation in a crystallization-enhanced deracemization process is reported. During this process, complete and rapid deracemization of chiral conglomerate crystals of an isoindolinone is attained through fast microwave-assisted temperature cycling. A parametric study of the main factors that affect the occurrence of secondary nucleation in this process, namely agitation rate, suspension density, and solute supersaturation, confirms that an enhanced stereoselective secondary nucleation rate maximizes the deracemization rate. Analysis of the system during a single temperature cycle showed that, although stereoselective particle production during the crystallization stage leads to enantiomeric enrichment, undesired kinetic dissolution of smaller particles of the preferred enantiomer occurs during the dissolution step. Therefore, secondary nucleation is crucial for the enhancement of deracemization through temperature cycles and as such should be considered in further design and optimization of this process, as well as in other temperature cycling processes commonly applied in particle engineering.  相似文献   
98.
The effect of humidity on the holographic grating diffraction efficiency and transmittance kinetics in the E204Q BR gelatin film is investigated. We found a correlation between the accumulation of the red-light absorbing O intermediate in the later part of the E204Q BR photocycle and sharpness (decay to the steady-state) of the holographic recording kinetics. As shown, at humidity exceeding 95% the ratio between the peak and steady-state of the diffraction efficiency for the weak probe beam (670 nm) can reach 8.7 in the E204Q BR film, which is sufficient for realization of an efficient novelty filter.  相似文献   
99.
The production of ligno-cellulosic biomass-based composites requires the development of new methodologies to evaluate the reinforcement potential of a given biomass, such as miscanthus studied in the work. Miscanthus stems from thirteen genotypes were broken into elongated fragments and mixed with polypropylene composites in an internal mixer. The aim is to find the best protocol able to discriminate miscanthus genotypes for their reinforcement capability. The following process parameters were optimized in order to maximize the reinforcement effect of the stem fragment filler: mixing parameters (mixing time, rotor speed and chamber temperature), temperature, fragment content, size and length distributions and coupling agent. The relationship between the process parameters and the mechanical properties of composites were analyzed to evaluate the influence of genotype on reinforcement performance, showing the robustness of the protocol in effectively discriminating genotypes according to their reinforcing capacity.  相似文献   
100.
Certain diseases are known to cause changes in the physical and biomechanical properties of cells.These include cancer,malaria,and sickle cell anemia among others.Typically,such physical property changes can result in several fold increases or decreases in cell stiffness,which are significant and can result in severe pathology and eventual catastrophic breakdown of the bodily functions.While there are developed biochemical and biological assays to detect the onset or presence of diseases,there is always a need to develop more rapid,precise,and sensitive methods to detect and diagnose diseases.Biomechanical property changes can play a significant role in this regard.As such,research into disease biomechanics can not only give us an in-depth knowledge of the mechanisms underlying disease progression,but can also serve as a powerful tool for detection and diagnosis.This article provides some insights into opportunities for how significant changes in cellular mechanical properties during onset or progression of a disease can be utilized as useful means for detection and diagnosis.We will also showcase several technologies that have already been developed to perform such detection and diagnosis.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号